The music video (directed by Hannah Lux Davis) was released on 23 April 2015 on YouTube. In the video, Jessie J heads to Barden University (the campus of UCLA) where she performs the ballad while watching the students go about their days while walking around the campus, while scenes from Pitch Perfect 2 are shown.

"Flashlight" received generally mixed reviews. In a less favourable review, Steven J. Horowitz of Billboard gave the song two stars out of five, saying: "prone to funny bone shout-singing on her more upbeat singles, Jessie J dials back her vocal force on the tepid "Flashlight", off the Pitch Perfect 2 soundtrack. The more subtle delivery would be welcome if the track weren't so paint-by-numbers, it plays like a pantomime of a Sia ballad, but without the emotive edge."
The song is first sung by Barden University freshman Emily (Hailee Steinfeld) for her audition into the Barden Bellas, who have been suspended from competition. Emily explains that she writes songs to compensate for her anxieties, in this case, leaving home. Emily sings the song again later during the "Riff Off" which, due to it being an original song, causes the Bellas to be disqualified.

Upon learning that Emily writes her own songs, Beca (Anna Kendrick) offers to work with her on it and record the song in a studio.

At the climax of the film, the Bellas incorporate "Flashlight" into their World Championships setlist.